Mounts the Audiobookshelf-compatible API on its own http.Server so
discovery probes (/ping, /healthcheck, /status, /login, /socket.io)
own the URL space at the root without colliding with silo's SPA
fallback. Mirrors the Jellyfin compat pattern at :8096.
Also adds the ABSRecommender adapter, wired into ABSHandlerDeps via
recommendations.NewRepo + catalog.DetailService. The recommender file
was previously untracked; service.go has already been referencing
ABSRecommender, so HEAD did not build without it.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
